ppapi/shared_impl/time_conversion.cc

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "ppapi/shared_impl/time_conversion.h"
   6
   7 namespace ppapi {
   8
   9 namespace {
  10
  11 // Since WebKit doesn't use ticks for event times, we have to compute what
  12 // the time ticks would be assuming the wall clock time doesn't change.
  13 //
  14 // This should only be used for WebKit times which we can't change the
  15 // definition of.
  16 double GetTimeToTimeTicksDeltaInSeconds() {
  17   static double time_to_ticks_delta_seconds = 0.0;
  18   if (time_to_ticks_delta_seconds == 0.0) {
  19     double wall_clock = TimeToPPTime(base::Time::Now());
  20     double ticks = TimeTicksToPPTimeTicks(base::TimeTicks::Now());
  21     time_to_ticks_delta_seconds = ticks - wall_clock;
  22   }
  23   return time_to_ticks_delta_seconds;
  24 }
  25
  26 }  // namespace
  27
  28 PP_Time TimeToPPTime(base::Time t) { return t.ToDoubleT(); }
  29
  30 base::Time PPTimeToTime(PP_Time t) {
  31   // The time code handles exact "0" values as special, and produces
  32   // a "null" Time object. But calling code would expect t==0 to represent the
  33   // epoch (according to the description of PP_Time). Hence we just return the
  34   // epoch in this case.
  35   if (t == 0.0)
  36     return base::Time::UnixEpoch();
  37   return base::Time::FromDoubleT(t);
  38 }
  39
  40 PP_TimeTicks TimeTicksToPPTimeTicks(base::TimeTicks t) {
  41   return static_cast<double>(t.ToInternalValue()) /
  42          base::Time::kMicrosecondsPerSecond;
  43 }
  44
  45 PP_TimeTicks EventTimeToPPTimeTicks(double event_time) {
  46   return event_time + GetTimeToTimeTicksDeltaInSeconds();
  47 }
  48
  49 double PPTimeTicksToEventTime(PP_TimeTicks t) {
  50   return t - GetTimeToTimeTicksDeltaInSeconds();
  51 }
  52
  53 double PPGetLocalTimeZoneOffset(const base::Time& time) {
  54   // Explode it to local time and then unexplode it as if it were UTC. Also
  55   // explode it to UTC and unexplode it (this avoids mismatching rounding or
  56   // lack thereof). The time zone offset is their difference.
  57   base::Time::Exploded exploded = {0};
  58   base::Time::Exploded utc_exploded = {0};
  59   time.LocalExplode(&exploded);
  60   time.UTCExplode(&utc_exploded);
  61   if (exploded.HasValidValues() && utc_exploded.HasValidValues()) {
  62     base::Time adj_time = base::Time::FromUTCExploded(exploded);
  63     base::Time cur = base::Time::FromUTCExploded(utc_exploded);
  64     return (adj_time - cur).InSecondsF();
  65   }
  66   return 0.0;
  67 }
  68
  69 }  // namespace ppapi